1. Field of the Invention
The present invention concerns a tire used for cars or like other vehicles and, more in particular, it relates to a tire capable of improving running stability and performance.
2. Description of the Prior Art
Tires used for vehicles such as cars are usually charged with pressurized air at the inside of an air tube contained in a tire or directly in an airtight plenum of a tire for absorbing shocks exerted from a road surface.
Further, such a pneumatic tire also has an important concern on the running stability and steering performance and they are controlled by adjusting the pressure of air charged in the tire. The tire also has a more important concern with a braking operation, in particular, emergency braking during high speed running of a car. It is highly desirable that a braking distance from the initiation of a braking operation till the complete stopping of the car is as short as possible from a safety point of view.
As far as a tire is concerned, the braking distance can be shortened, generally, by forming a grooved pattern of an appropriate design on a tread surface of a tire so as to increase a frictional resistance or ground gripping effect of the tire.
The grooved pattern formed on the tread can surely provide increased frictional resistance relative to the road surface, but it is not yet completely sufficient for providing satisfactory effect upon emergency braking. A car tire readily suffers from denaturation and deformation (abrasion) due to heat of friction generated between the tire and the load surface. Then, the grooved rubber tread is gradually made flat to lose its road gripping effect.
It has also been attempted recently to provide a rolled friction sheet adapted to be rapidly released upon emergency braking and spread between the tire and the road surface, thereby compulsorily forming anti-skid friction between them. However, use of the rolled frictional sheet may be reliable but it complicates the structure of a car.